In the 1998 film "Armageddon," the character played by Bruce Willis saves the Earth by knocking aside an asteroid headed straight for us. Pure fiction, right? Well, maybe not.

Last month's meteor explosion over Russia was a reminder of just how vulnerable we are to those large rocky bodies whizzing by in outer space. Well, we hope they're whizzing by. The Siberian version of "Armageddon," though, says, what happens when they don't? Well, scientists are working to protect us. How?

DR. ANDREW CHENG: By crashing a spacecraft into an asteroid to change its orbit.

LYDEN: That's Dr. Andrew Cheng, chief scientist of the space department at Johns Hopkins University's Applied Physics Lab. He's heading up a project that could have been ripped from a Hollywood screenplay. Here's the idea: Shoot a rocket into an asteroid, knock it off course.

CHENG: The idea is almost the same as what a hockey player does if there's an opposing player coming at you that you don't want to come too close to your goal. You just go out and hit him with your body and just push him off to the side.

LYDEN: The project is aiming for an asteroid called Didymos, which is Greek for twin because Didymos is actually two asteroids.

CHENG: There's a fair number of the near-Earth asteroids which have their own little moons around them. This is one of those, and we're going to target the moon of the asteroid Didymos. We want to pick on the little guy because the little guy's easier to shove around.

LYDEN: Cheng says that if Didymos were to hit the Earth, it would cause damage on the scale of a nuclear war. But not to worry. Near-Earth is a relative term. Didymos is projected to pass six and a half million miles away from us and not for another decade.

CHENG: We need that much time to get ready and also to convince the national agencies that this is worth doing.

LYDEN: Right now, the project named AIDA for Asteroid Impact and Deflection Assessment is in the conceptual stage, but it has the support of both NASA and the European Space Agency. And forgive us here, the stars have to align for all that funding to come through. Cheng says this is really important, a defense measure.

CHENG: If, for example, an asteroid were discovered, even a very hazardous one that were going to hit the Earth, say, in five or six months, you know, there's nothing we could do to prevent the impact.

LYDEN: As for the impact in Siberia last month, which injured 1,000 people, those kinds of collisions really aren't as rare as one might hope?

CHENG: That size impact occurs roughly once every 100 years. So we don't know when or where the next impact of that size would happen.

(SOUNDBITE OF MOVIE, "ARMAGEDDON")

ANDERSON: (as the President) The Bible calls this day Armageddon. For the first time in the history of the planet, the species has the technology to prevent its own extinction.

LYDEN: OK. "Armageddon" is just a movie. And while the technology is a work in progress at the Johns Hopkins Applied Physics Lab, Cheng won't get to save the planet anytime soon. He says that catastrophic strikes from asteroids the size of mountains only happen once every few million years. Tell that to the dinosaurs.